hello, I need RS232 to RS485 converter. which IC should I use??
Basically, any RS-232 and RS-485 transceivers. For example, MAX3232 and SN75176. You have to find a way to supply the 'Receiver Enable' and "Driver Enable' signals to the RS-485 transceiver. Apparently, the RTS signal or RS-232 is used for that in some setups.
first; why not just buy a good one from www.bb-elec.com/Subcategory.asp
second: BB does have schematics publicly accessible that should give you some ideas
Erik